1. Field of the Invention
The present invention generally relates to display devices, and particularly relates to a display device which allows complex image information such as letters and pictures to be displayed and input via a liquid crystal display.
2. Description of the Related Art
In recent years, development of information technology has created a demand for a small-size display device which allows complex information to be displayed and input via screen.
FIG. 1 is a block diagram of a liquid crystal display device (hereinafter referred to as an LCD device) as an example of a related-art display device.
In FIG. 1, an LCD 200 includes operation circuits CIR1 through CIR2m, the total number of which is 2m. Each of the operation circuits CIR1 through CIR2m includes a driver, a check circuit, a tablet detection circuit, etc. The LCD 200 further includes a display unit 2 which displays information on an LCD screen.
The LCD 200 is connected to a control device 150, which controls operations of the LCD 200. A plurality of signal lines connect between the control device 150 and the LCD 200 to exchange information therebetween. When a display operation is to be performed, drivers of the operation circuits operate based on information supplied from the control device 150 so as to activate a liquid crystal element corresponding to the supplied information. When input is entered via a pen touch on the display unit 2, information corresponding to a position of the pen touch is forwarded from coordinate-detection circuits of the operation circuit to the control device 150.
The number of signal lines connecting between the control device 150 and the LCD 200 needs to be the total number of bits of all the operation circuits. When each of the 2m operation circuits CIR1 through CIR2m has a n-bit configuration, for example, the number L0 of the signal lines between the control device 150 and the LCD 200 needs to be 2m×n.
Since the signal lines between the control device 150 and the LCD 200 are as many as the total number of bits of the operation circuits, the following problem is encountered in such a configuration. That is, when the LCD 200 is designed for displaying and inputting of complex information, the number of the operation circuits and the number of bits of each operation circuit are increased. In such a case, the number of signal lines and the number of connection terminals become larger, resulting in a cost increase regarding signal-line connections. Further, an increase in the number of terminals leads to the number of components for the LCD 200 and the control device 150 being increased. This means a rise in manufacturing costs of the LCD 200 and the control device 150, and, also, results in the LCD 200 and the control device 150 having larger sizes.
In consideration of this, the operation circuits of the related-art LCD 200 tend to employ a simple structure, giving priority to miniaturization of the LCD 200 over enhanced functions of displaying and inputting of sophisticated information.
Accordingly, there is a need for a display device which allows complex information to be displayed and input via a screen thereof without increasing the number of signal lines between the display device and a control circuit as well as the number of circuit components of the display device and the control circuit.